Recent mobile phones and other devices may typically incorporate a micro electro-mechanical systems (MEMS) microphone.
A MEMS microphone includes an acoustic transducer fabricated using MEMS technology, and an application specific integrated circuit (ASIC) for amplifying an output of the acoustic transducer, which are together accommodated in a housing.
As shown in FIG. 1A, an acoustic transducer known in the art included in a MEMS microphone may include a substrate 32 having a cavity 32a, a vibration electrode plate (diaphragm) 33 arranged on the substrate 32 to close the cavity 32a, and a stationary electrode plate 39 facing the vibration electrode plate 33.
In this acoustic transducer, the vibration electrode plate 33 transfers vibrations from its portion located on the substrate 32 toward its middle portion. The acoustic transducer shown in FIG. 1A thus has high acoustic resistance in the space between the substrate 32 and the vibration electrode plate 33. This can cause acoustic noise.
The vibration electrode plate 33 may physically separate its portion located on the substrate 32 from its middle portion to avoid direct transfer of vibrations from the portion located on the substrate 32 to the middle portion. For example, an acoustic transducer may include a vibration electrode plate 33 having a plurality of slits 37 around its middle portion as shown schematically in FIG. 1B.